x86: zboot: Move zimage definitions to the header file

In preparation for splitting the zboot-command code into a separate
file, move the definitions into the header file.

While we are here, mention when load_address and base_ptr are set up
and explain bzimage_addr better. Make cmdline const since it cannot be
changed.

Signed-off-by: Simon Glass <sjg@chromium.org>
2 files changed